Which dietary modifications are used in the treatment of nephrolithiasis?

Updated: Jun 21, 2018
  • Author: Chirag N Dave, MD; Chief Editor: Bradley Fields Schwartz, DO, FACS  more...
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Answer

In almost all patients in whom stones form, an increase in fluid intake and, therefore, an increase in urine output is recommended. This is likely the single most important aspect of stone prophylaxis. Patients with recurrent nephrolithiasis traditionally have been instructed to drink 8 glasses of fluid daily to maintain adequate hydration and decrease chance of urinary supersaturation with stone-forming salts. The goal is a total urine volume in 24 hours in excess of 2.5 liters.

The only other general dietary guidelines are to avoid excessive salt and protein intake. Moderation of calcium and oxalate intake is also reasonable, but great care must be taken not to indiscriminantly instruct the patient to reduce calcium intake. Patients with calcium stones and relatively low urinary citrate should increase their intake of fruits and vegetables.

Dietary calcium should not be restricted beyond normal unless specifically indicated on the basis of on 24-hour urinalysis findings. Urinary calcium levels are normal in many patients with calcium stones. Reducing dietary calcium in these patients may actually worsen their stone disease, because more oxalate is absorbed from the GI tract in the absence of sufficient intestinal calcium to bind with it. This results in a net increase in oxalate absorption and hyperoxaluria, which tends to increase new kidney stone formation in patients with calcium oxalate calculi.

An empiric restriction of dietary calcium may also adversely affect bone mineralization and may have osteoporosis implications, especially in women. This practice should be condemned unless indicated based on a metabolic evaluation.

As a rule, dietary calcium should be restricted to 1000-1200 mg/d in patients with diet-responsive hypercalciuria who form calcium stones. This is roughly equivalent to a single high-calcium or dairy meal per day.


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